A dual view liquid crystal display can simultaneously display an image having a first viewing angle and an image having a second viewing angle different from the first viewing angle. In other words, the viewing angle of the liquid crystal display monitor is controlled, thus enabling simultaneously displaying different information or contents on the right and left sides thereof.
Therefore, when a dual view liquid crystal monitor is used as a display monitor of a navigation system, one LCD can display visuals different from each other on the right and left sides of the display, respectively, in such a way that a navigation screen, for example, can be seen by an occupant on a driver's seat side and a DVD (Digital Versatile Device) cinema screen can be seen by another occupant on a passenger seat side.
Further, the dual view liquid crystal can form a display-input apparatus by being combined with an operation face (touch panel) disposed on the front face of a display panel, and it becomes possible for an occupant including a driver to communicate with the main body of a navigation system by touching an icon menu or the like displayed on the dual view liquid crystal. For this reason, a touch panel is mounted on a navigation system as a human interface having an excellent operability separately from a console or a remote controller in existence and has been distributed to the market as a touch-panel-equipped navigation system.
Meanwhile, in a conventional touch-panel-equipped navigation system using a dual view liquid crystal, icons having the same menu configuration are displayed on both of the screen viewed from a driver's seat side (hereinafter, referred to as a driver's seat side screen) and the screen viewed from a passenger seat side (hereinafter, referred to as a passenger seat side screen). However, a menu of which all items can be selected is displayed on the passenger seat side screen, while a menu containing operation-restricted items in part is displayed on the driver's seat side screen, with the operation-restricted items being displayed with colors or designs different from those of other items.
In this case, it is necessary for the main body of the navigation system to make a determination about which of the images the operation performed to only one touch panel is effective to and exercise the display control such that each of the occupants can see and listen to the desired content by performing touch operation even during performing a dual view display.
However, it is very difficult to make a determination about which occupant carried out the operation. The method such as providing, for example, a selector switch thereon seems like a useful one. But, whenever the touch panel is operated, operating the selector switch is required. This increases the complexity of the operation and disadvantageously loses the advantage of the touch panel of allowing an intuitive touch operation.
For this reason, conventionally, a display system is disclosed, where a touch panel is placed in a state where an area exclusively used by the touch of a viewer A and an area exclusively used by the touch of a viewer B are separated therefrom so as not to be in a superposed relation and a determination about which viewer operated can be made depending on the operating area (see Patent Document 1 and Patent Document 2, for example).    Patent Document 1: JP-A-2005-071286 (Paragraph “0011” and FIG. 1)    Patent Document 2: JP-A-2005-284592 (Paragraphs “0010” to “0016,” and FIG. 2)
However, according to the technology disclosed in Patent Document 1 and Patent Document 2, the operation area is merely separated and allocated to each of the viewers (the occupants including the driver), and for example, if the viewer A wrongly operates the operation area assigned to the viewer B, the operation is misjudged to be the operation of the viewer B, with the display on the side of the viewer B being switched to an unintended one.
Thus, according to the conventional touch-panel-equipped navigation system, a determination about which image the operation of the touch panel is effective to is not made. Accordingly, if the icon to which the operation performed is effective to the image on the other side that is not actually viewed from the left side (the right side in the case of a left-hand drive vehicle) is displayed, the operation to the icon can be accidentally carried out by touching the corresponding place.
To be more specific, if an operation-restricted item in the driver's seat side screen is in a superimposed relation with a selectable item in the passenger seat side screen, the operation from the driver's seat side causes the passenger seat side screen to be operated. There is a problem that the image on the passenger seat side is switched to an unintended one.
The present invention has been made to solve the above-mentioned problems, and objects of the present invention are to provide a display system where the occurrence of the situation where an unintended image is displayed on the passenger seat side is prevented by making a determination about which of an occupant on the driver's seat side and an occupant on the passenger seat side operated a touch panel while a dual view is displayed, and further to provide a method of restricting operation in the display system.